Post on 14-Jan-2017
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Flexible vs. Rigid Couplings
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q This webinar will be available afterwards at www.designworldonline.com & email
q Q&A at the end of the presentation q Hashtag for this webinar: #DWwebinar
Before We Start
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Mike Santora Associate Editor - Moderator Design World
Edward Cole Engineering Manager Ringfeder Power Transmission USA Corp.
Andy Lechner Product Manager R+W America
Flexible vs. Rigid Couplings
Bobby Watkins Vice President of Sales Ruland Manufacturing Co. Inc.
Meet the speakers…
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PARALLELSHAFTMISALIGNMENT
• resultsfromlackofpilotsinmoun>ngframes/couplinghousings• mostharmfultobearingsandcouplings• evensmallamounts(e.g.,>0.001”)canplacealargeamountofstressonadjacentshaNbearings,contributetovibra>on,andreducesystemefficiency
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ANGULARSHAFTMISALIGNMENT
• resultsfrommoun>ngsurfacesnotbeingflatorlevel• slightlylessharmfultobearingsandcouplings• rarelyexistswithoutparallelmisalignment
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AXIALSHAFTMISALIGNMENT(ENDPLAY)
• resultsfromthermalexpansionofshaNing• resultsfrommotorshaNend-play• occurstovaryingdegreesindependentofothertypesofmisalignment
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MOUNTINGWITHPILOTS
• protrudingfeatureofaprecisiondiameterandconcentrictotheshaN• existsonalmostallservomotors,steppermotorsandprecisiongearboxes• whenusedinconjunc>onwithaprecisionmachinedhousing,parallelshaNalignmentwithin0.001-0.003”shouldbeguaranteed
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RIGIDCOUPLINGS
• disclaimer–R+Wdoesnotmakerigidcouplings• veryusefulinjoiningshaNswhicharenotbothbearingsupported
• allowsoneshaNtosupporttheother• nomisalignmentloadingifonlyoneshaNisbearingsupported
• usefulwhenoneconnectedcomponenthasaflexibleframe• (e.g.,encoderswithflexiblemounts)• allowsthatcomponenttoflexduringshaNrota>ontocompensateformisalignment
• some>mesusedtocouplealengthofshaNingoneachend• workswellwhentheshaNislongenoughtoflexslightly• mostlyforslowerrota>onalspeeds
• oNenusedincaseswherehighprecisionrota>onisneededbutthenrequiredifficultalignmentprocedures
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FLEXIBLECOUPLINGS
• disclaimer–R+Wdoesmakeandsellflexiblecouplings• generallyconsideredtobeabestprac>cebetweensupportedshaNs
• reducessideloads,whichares>llhighat0.001”misalignment• helpsextendbearinglife• canhelpwithvibra>ondamping
• manyvarie>esandmoun>ngop>onsareavailableonthemarket• torsionallyrigidversions• vibra>ondampingversions• highmisalignmentversions• self-suppor>nglineshaNversions
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BACKLASH
• mechanicalclearancewhichresultsinlostmo>on• necessaryinmostgears,butcanbeavoidedinflexiblecouplings
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TORSIONALWIND-UP
• momentarydeflec>onasaresultoftorqueloading• occurstovaryingdegreesinalldrivecomponentsbutisgenerallygreaterinflexiblecouplingsthaninrigidcouplings
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BELLOWSCOUPLINGS
• unlikeother“spring”typecouplingstheyaretorsionallyrigid• usedtypicallyinhighlydynamicorhighprecisionapplica>ons• offersthebenefitsofreducedbearingloadswithhighperformance• s>llnotastorsionallys>ffasrigidcouplingsbutworthconsidering
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PRECISIONELASTOMERCOUPLINGS
• torsionallysoNforvibra>ondampingbutpreloadedforzerobacklash• offerscompensa>onforsmallamountsofshaNmisalignment• hightorquedensitycomparedwithotherflexiblecouplingtypes
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EXAMPLE:BALLSCREW/LEADSCREWAPPLICATION
• GIVEN:10Nmtorqueload/10mmlead• 10Nmbellowscoupling
• torsionals>ffnessof157Nm/deg=0.064°angulardeflec>on• witha10mmleadthisresultsin0.0018mm(0.00007”)linearerror
• 10Nmelastomercoupling(standardinsert)• sta>ctorsionals>ffnessof4.54Nm/deg=2.2°angulardeflec>on• witha10mmleadthisresultsin0.0611mm(0.00241”)linearerror
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THANKSFORYOURTIME!
Selecting Couplings For Your Servo Applications
Ed Cole, Engineering Manager
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Servo Coupling Requirements!• Backlash-free to maintain positioning accuracy.
• Mass balanced for high rotational speeds.
• Designed for low to moderate torques—usually to 100 Nm.
• Tolerant of shaft misalignments.
• Maintenance free.
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Servo Coupling Applications!• Any automation system with shaft-driven linear motion, including:
• Machine tools.
• Packaging equipment.
• Test and measurement systems.
• Semiconductor manufacturing.
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Servo Coupling Choices!• Two types of servo couplings can meet these requirements:
• Rigid metal bellows couplings.
• For example, Ringfeder Gerwah EKN and DKN Series.
• Flexible servo insert couplings.
• For example, Ringfeder Gerwah GWE Series.
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Servo Coupling Choices!• Many servo applications do not strongly favor one type of coupling over another.
• Either a metal bellows and servo insert coupling can satisfy basic torque, shaft size and lifecycle requirements.
• But each type of coupling has its subtle advantages:
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Metal Bellows Coupling!• Typically constructed of stainless steel bellows with aluminum hubs.
• Integrated clamping hubs or set screws in miniature models.
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Metal Bellows Coupling!
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Servo Insert Coupling!• Typicallyconsistsofaluminumhubsandelastomer“spider”inserts.
• Clampingviasetscrewsorintegratedclampinghub
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• Adjustable flexibility by changing elastomer inserts.
• Harder inserts approach metal bellows stiffness.
• Softer inserts maximize damping and misalignment tolerance.• Optimize vibration damping through insert selection.
• Excellent tolerance of radial, axial and angular misalignment.
• Good torque transmission and angular positioning performance.
Servo Insert Coupling!
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Servo Insert Coupling Application!
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• Keep in mind that servo couplings often work in conjunction with other power transmission components, such as gear boxes and linear actuators.
• It’s important to choose couplings whose designs work well with related power transmission components.
• Shrink discs
• Locking assemblies
Couplings Are Part Of A System!
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Couplings Are Part Of A System!
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Couplings Are Part Of A System!
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Metal Bellows Servo Insert
Product Examples! EKN, DKN, AKN Series! GWE Series!
Adjustable Rigidity!
Torque Transmission!
Backlash Free!
Misalignment Tolerance!
Damping!
Low Inertia!
Servo Couplings At A Glance!
Thank You Ed ColeEngineering Manager
Tel: (201) 666-3320
Email: edward.cole@ringfeder.com
#DWwebinar Presentedby:BobbyWatkins www.ruland.com
Flexible vs. Rigid Couplings
Presentedby:BobbyWatkins www.ruland.com
#DWwebinar Presentedby:BobbyWatkins www.ruland.com
Types of Misalignment
Presentedby:BobbyWatkins www.ruland.com
#DWwebinar Presentedby:BobbyWatkins www.ruland.com
Why is misalignment a concern?
• Addsstresstosystemcomponents
• Causedbytolerancemismatch
#DWwebinar Presentedby:BobbyWatkins www.ruland.com
Backlash, Windup, and Bearing Loads
CouplingwithWindup • Windupisnotbacklash• Backlashreferstopowertransmissionerror• Windupisposi>onerrorwithouttorqueerror• Allcouplingshavewindup• Zero-backlashmeanszerolossinpowertransmission
• Bearingloadsincreasewear• Excessivebearingloadsresultinbearingwearand
• prematurefailure• Couplingsdesignedtoflexduringmisalignmentproducebearingload
• Couplingmisalignmentra>ngsoNenresultfrombearingloads
CouplingwithMisalignment
#DWwebinar Presentedby:BobbyWatkins www.ruland.com
Bearing Loads
• Misalignmentexistsbetweenthemotorandthedrivensystemduetotolerancesand/orsystemincompa>bility
• Bearingloadsaregeneratedasaresultandareharmfultosystemperformance
• Othersystemdesignfactorsmustbeconsideredwhenselec>ngacoupling
#DWwebinar Presentedby:BobbyWatkins www.ruland.com
Managing Misalignment
• Selec>onofthecorrectcouplingiscri>cal
• Mustaddresstheapplica>onmisalignmenttypeortypes
• Muststaywithinthecouplingspecifica>ons
• Mustinstallthecouplingproperly
• Otherapplica>oncriteriamustalsobeaddressed
#DWwebinar Presentedby:BobbyWatkins www.ruland.com
Rigid Couplings
Benefits• Besttorquetransmissioncapabili>es
• Almostzero-windup=themostprecisecouplingavailable
• SuitableforshaNsupportandpush-pullapplica>ons• Lowcost
Drawbacks• Nomisalignmentcapabili>es
• Noallowanceforthermalexpansion
• Extremelyhighbearingloadsifusedincorrectly
• Poten>alfordamagetosystemcomponents
• Veryhighiner>a-notsuitableforhighRPMapplica>ons
#DWwebinar Presentedby:BobbyWatkins www.ruland.com
Flexible Couplings
Benefits• Accommodatemisalignment
• Differentstylesallowtheusertoselectthebestfitfortheapplica>on
• HighRPMcapabili>es
• Manystandardsizeop>onsareavailable
• Mosthavelowiner>a
Drawbacks• Somerequiremaintenance
• Installa>oncanrequirespecializedalignmentsystems
• Limitedtorquecapabili>es
• BothshaNsmustbebearingsupported
• Highcost
OldhamCoupling BellowsCouplingBeamCoupling JawCoupling DiscCoupling
#DWwebinar Presentedby:BobbyWatkins www.ruland.com
Product SelecFon
• Mul>plesolu>onsmayexistwhenselec>ngacoupling
• Specificcouplingsarebesersuitedforeachtypeofmisalignment,forexample:oldhamswithparallelmisalignmentorbeamcouplingsforangularmisalignment
• Bearingloadsandwindupareasideeffectofallcouplings
• Propercouplingselec>onrequiresafullunderstandingofthesystemrequirements
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Mike Santora Associate Editor - Moderator Design World @DW_MikeSantora
Edward Cole Engineering Manager Ringfeder Power Transmission USA Corp. Edward.cole@ringfeder.com
Andy Lechner Product Manager R+W America Alechner@rw-america.com
Flexible vs. Rigid Couplings
Bobby Watkins Vice President of Sales Ruland Manufacturing Co. Inc. Robert.watkins@ruland.com
Questions?
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Thank You q This webinar will be available at
designworldonline.com & email
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